The Hindu Business Line : IMD stands by normal monsoon forecast, sees 97 pc rainfall in July

In its updated forecast issued on Wednesday, the IMD said the rainfall for the month would be 97 per cent of its Long Period Average (LPA) with a model error of plus or minus 9 per cent.

The IMD has also issued a long-range forecast update for this year's season (June-September), which estimated the seasonal rainfall to be 98 per cent of the LPA with a model error of plus or minus 4 per cent.

The probabilistic model suggested a very high (70 per cent) probability for the seasonal rainfall to be near normal and above.

In its region-wise break-up for the season, the forecast indicated rainfall as being 97 per cent of its LPA over northwest India, 95 per cent over northeast India, 102 per cent over central India and 97 per cent over the southern peninsula, all with a model error of plus or minus 8 per cent.

Break monsoon averted: Meanwhile, the `strength of character' displayed by the 10-day-old monsoon depression is now believed to have helped it stand up gamely to an invading western disturbance, averting a possible `break monsoon' during a crucial phase of the season.

On the flip side, this longevity may have also delayed the formation of a fresh low-pressure over the Bay of Bengal by at least a day, Dr Akhilesh Gupta, Director, National Centre for Medium Range Forecasting (NCMRWF), told Business Line.

Two monsoon systems are not known to coexist normally for reasons of unfavourable external dynamics.

The NCMRWF had earlier predicted that the second `low' would take shape by Wednesday. According to Dr Gupta, a cyclonic circulation lay over northwest Bay on Wednesday afternoon, in anticipation of the `low'. This is likely to descend and concentrate into a low-pressure area in tandem with the depression, already weakened to a well-marked `low' and lying over southwest Uttar Pradesh, losing further steam and moving in a north-north-westerly direction.

Reversal of roles: Explaining the dynamics of the interaction of a tropical system (monsoon depression) and an extra-tropical system (western disturbance), Dr Gupta said the invading westerlies normally sway the weakening depression and drag it along their eastward course. But, in a unique reversal of roles, the prevailing monsoon system managed to hold on its own. All major climate models are now showing a clear `detachment' of the two systems, which is rare.

Significantly, the detachment has resulted in the systems moving away from each other and in opposite directions. The westerlies are seen tracking their eastward-bound course leading to precipitation in the foothills of Uttar Pradesh and Bihar while the monsoon system is moving in a north-northwestward direction, raining all the way in Haryana and East Rajasthan.

A possible `break monsoon' phase has been averted, since a pliable monsoon system could otherwise have been dragged into the foothills with the all-important monsoon trough in tow. Various models suggest that the monsoon trough is in tact and in its normal position, and would continue to do so, no matter what becomes of the western disturbance. This is the most propitious development for the southwest monsoon. This could be one reason why all these models, including that run by the IMD, suggest normal July rainfall for the country as a whole.

One major worry is the lack of rainfall activity (deficient or scanty) over Jharkhand, Bihar, Marathwada and southern parts of the northeastern States - Nagaland, Manipur and Mizoram. Of these, Bihar has large areas where paddy is grown. According to Dr Gupta, the NCMRWF has issued advisories that the paddy variety used for sowing may be changed if the areas don't get rain even by July 15.

In Marathwada, the rainfall deficit has been estimated to be minus 68 per cent. But the models suggest that the central and south-central parts of the country would get good rainfall during July. It is hoped Bihar and Marathwada would also be brought under rain cover during this spell.

Article E-Mail :: Comment :: Syndication :: Printer Friendly Page

Stories in this Section
IA launches `Easy Fares' scheme

IMD stands by normal monsoon forecast, sees 97 pc rainfall in July

`Private oil cos may be asked to bear part of subsidy burden'

No stake for foreign airlines in domestic carriers: Govt
Policy to specify norms for ground handling

Govt opens up lignite blocks for captive power production

Infosys places Rs 4,600-cr cover with NIC

Advance tax payment of top taxpayers to be `monitored'

Pvt bank stocks shine; Sensex soars

RBI sets up dept to track financial markets

AGM & `problem' shareholders — CESC's way of keeping them at safe distance